The present invention relates generally to the field of vascular surgery and, more specifically, to a branching device or a graft connector for blood vessels, especially for bypass operations on the coronary vessels. The invention is also related to an instrument for introducing the graft connector into a blood vessel and further to a combination of a graft connector and an introducer. Further, the invention relates to a method of making a branch connection to a blood vessel.
An increased flow resistance in the various coronary vessels can jeopardise the oxygen supply to the cardiac muscle. In some cases an expansion of vascular stenosis is possible. If the flow of blood in a vessel is completely or practically completely blocked, the only thing to be done is to bypass the blocked portion to prevent an irreparable injury from arising. Such a bypass operation is usually effected by connecting a new vessel after the blocked point and connecting it to another blood vessel, for instance the aorta, which may give a sufficient flow of blood to the blood vessel after the blocked point.
In practice, such a bypass operation requires the use of a heart-lung machine, i.e. that the heart be temporarily stopped since the bypass operation when connecting, for instance, the two vessels involved requires the heart to be immovable. In consequence of the connecting technique employed and the use of the heart-lung machine, the operation will be relatively time-consuming and not completely without risk.
When larger vessels are involved, it is known from e.g. U.S. Pat. No. 5,456,712 to provide a branch by blocking the vessel by means of balloons on each side of the intended branch point, whereupon an incision is made in the blocked portion of the blood vessel. Then an expanded end of a vascular prosthesis is inserted through the incision and a stent is inserted through the one blocking balloon to a position inside the incision, where finally the stent is expanded by means of a further balloon positioned inside the stent. For completely safe fixing of the expanded end to the area around the incision in the vessel, some sort of suture is used, primarily for connecting the expanded end of the vascular prosthesis with the blood vessel around the incision therein.
This prior-art technique implies that a blocking can be made on each side of the intended branch point, and that the stent can be inserted via the diseased vessel involved and through one of the blocking balloons. In practice, also a fixing of the expanded end of the vascular prosthesis relative to the vessel involved by means of some sort of suture is required.
The technique according to U.S. Pat. No. 5,456,712 is thus not suited for use in thin vessels, such as the coronary vessels, or in other positions where the described blocking by means of a balloon from the inside of the vessel is not possible.
A more a simple and reliable bypass of the coronary vessels without necessitating temporary internal blockings is disclosed as a branching device in WO97/43961. This branching device has a sleeve, which is radially extensible and has an opening in its circumferential surface, and a collar which consists of a fluid-tight material and is fixed to the sleeve before the branching device is used and which has, on the one hand, a shoulder portion extending at least around the opening in the circumferential surface of the sleeve and, on the other hand, a neck portion integral with the shoulder portion and projecting radially from the opening in the circumferential surface of the sleeve.
The opening in the circumferential surface of the sleeve is preferably arranged unsymmetrically relative to the ends of the sleeve. This confers an advantage since the necessary longitudinal incision in the blocked vessel need not be made longer than the distance from the neck portion to the nearest end of the sleeve, while the sleeve of the branching device can be retained safely in the vessel thanks to the sleeve obtaining a long part (seen from the neck portion), which must thus first be inserted into the opening in the vessel.
After the insertion of the sleeve into the vessel in a reciprocating movement, the short part of the sleeve is positioned completely beyond the opening in the vessel, while the long part of the sleeve covers the main part of the opening in the vessel and besides can extend beyond this a distance of essentially the same length as the short part of the sleeve. Once the sleeve is correctly positioned in the vessel, its position is to be fixed. This is possible according to WO97/43961 thanks to the sleeve being radially extensible by means of a balloon and retaining its extended shape, i.e. the shape of the sleeve is permanently deformable. This results in an expansion of the vessel, which then clamps the sleeve in place and also clamps the shoulder portion of the collar against the sleeve.
An object of the present invention is to further improve the branching device disclosed in WO97/43961 and especially improve and simplify the insertion of a graft connector into a blood vessel.
This object is achieved by a graft connector having the features according to the accompanying claim 1, by an introducer having the features according to the accompanying claim 16, and by a combination having the features according to the accompanying claim 23. Also, the object is achieved by a method having the features according to any one of the accompanying claims 24-26.
Thus, the graft connector comprises a sleeve, which has an opening in its circumferential surface and comprises a memory material, a collar which consists of a fluid-tight material and is fixed to the sleeve before use of the graft connector and which has, on the one hand, a shoulder portion extending at least around the opening in the circumferential surface of the sleeve and, on the other hand, a neck portion integral with the shoulder portion and projecting radially from the opening in the circumferential surface of the sleeve, and removable means for temporarily reducing the diameter of the sleeve during insertion into a blood vessel.
The removable means may comprise a suture encircling at least part of the sleeve and thereby reducing the diameter of the sleeve.
Further, the graft connector may comprise edge means for cutting the suture once the sleeve is introduced into the blood vessel.
Preferably, the edge means comprises a needle having an edged hole at a tip thereof, through which hole the suture is extending.
Further, the graft may comprise two L-shaped elements, first releasable means for locking the two L-shaped elements together so as to form a T-shaped element having a stem and two oppositely directed arms, and second releasable means for connecting the arms of the T-shaped element along the sleeve of the graft connector. Thereby, the sleeve may be introduced into the blood vessel through the longitudinal incision made therein by manipulation of the stem of the T-shaped element and the two L-shaped elements may be released from each other and from the sleeve and then retracted from the blood vessel.
The suture should encircle at least part of the sleeve and the arms of the T-shaped element, which may have a longitudinal channel in which the needle is positioned.
The needle should be retractable from the longitudinal channel of the T-shaped element. Also, a cap may enclose the free ends of the stem in its non-retracted position. Further, the needle and the cap are locking the two L-shaped elements to each other.
According to the present invention, an introducer is provided for a T-shaped graft connector, which comprises a sleeve that is to be introduced into a blood vessel through a longitudinal incision made therein, the sleeve having an opening in its circumferential surface, and a collar adjoining the opening and extending radially therefrom and, when the sleeve is introduced into the blood vessel, extending out from the longitudinal incision made therein.
This introducer comprises two L-shaped elements, first releasable means for locking the two L-shaped elements together so as to form a T-shaped element having a stem and two oppositely directed arms, and second releasable means for connecting the arms of the T-shaped element along the sleeve of the graft connector, whereby the sleeve may be introduced into the blood vessel through the longitudinal incision made therein by manipulation of the stem of the T-shaped element and the two L-shaped elements may be released from each other and from the sleeve and then retracted from the blood vessel.
In such an introducer, the second releasable means for connecting the sleeve of the graft connector in parallel with the arms of the T-shaped element may comprise a suture encircling at least part of the sleeve and the arms of the T-shaped element.
Further, the second releasable means for connecting the sleeve of the graft connector in parallel with the arms of the T-shaped element may comprise an edge for cutting the suture.
More precisely, the second releasable means for connecting the sleeve of the graft connector in parallel with the arms of the T-shaped element may comprise a needle having an edged hole at a tip thereof, through which hole the suture is extending. The T-shaped element may have a longitudinal channel in which the needle is positioned.
Preferably, the needle is retractable from the longitudinal channel of the T-shaped element and has a cap enclosing the free ends of the stem in its non-retracted position. Also, the needle and the cap may lock the two L-shaped elements to each other.
According to the invention, a method of connecting the above described T-shaped graft connector to a blood vessel comprises the steps of locking the T-shaped element to the sleeve, reducing the diameter of the sleeve, making a longitudinal incision in the blood vessel, inserting the sleeve through the incision into the blood vessel using the stem as a holder, the collar extending radially out of the incision in the blood vessel, releasing the sleeve from the T-shaped element to allow the sleeve to expand within the vessel, and removing the T-shaped element from the blood vessel.
As an alternative, a method of making a branch connection to a blood vessel using the T-shaped graft connector and the T-shaped element comprises the steps of locking the T-shaped element to the sleeve such that the sleeve extends along the arms and the collar extends substantially along the stem, reducing the diameter of the sleeve, making a longitudinal incision in the blood vessel, inserting the sleeve through the incision into the blood vessel using the stem as a holder, the collar extending radially out of the incision in the blood vessel, releasing the sleeve from the T-shaped element to allow the sleeve to expand within the vessel, and removing the T-shaped element from the blood vessel.
Preferably, the T-shaped graft connector and the T-shaped element are already releasably locked to each other when delivered for introduction into a blood vessel. Then the method for making a branch connection to a blood vessel comprises the steps of making a longitudinal incision in the blood vessel, inserting the sleeve and the arms of the T-shaped element through the incision into the blood vessel using the stem as a holder, the collar extending radially out of the incision in the blood vessel, releasing the sleeve from the T-shaped element to allow the sleeve to expand within the vessel, and removing the T-shaped element from the blood vessel.
The locking of the T-shaped element to the sleeve may comprise at least partly encircling the sleeve and the arms with a suture, which may be released from the T-shaped element by cutting.
Alternatively, the locking of the T-shaped element to the sleeve may comprise inserting each one of the arms and an adjoining part of the sleeve into a tube made of a plastic film, e.g. made from PTFE, and then shrinking the tube thereby also reducing the diameter of the sleeve, which may be released from the T-shaped element by a longitudinal cut through the tube.
As a further alternative, the locking of the T-shaped element to the sleeve may comprise making a tube of each one of the arms and a sheet of a plastic film, said tube encircling an adjoining part of the sleeve, and reducing the diameter of the sleeve. Here, the diameter of the tube may be reduced by shrinking of the plastic film when the tube is made, whereby the diameter of the sleeve is reduced, or the diameter of the sleeve may be reduced at the same time as the tube is made.